


Bittersweet Infidelity

by placeholder000



Category: Undertale (Video Game)
Genre: Ecto-Penis (Undertale), F/M, Hate Sex, M/M, Reader isn't a good person, Self-Loathing, Smut, Swapfell, Swapfell Papyrus (Undertale), Swapfell Sans (Undertale), i can only write sins or angst apparently, implied fontcest
Language: English
Status: Completed
Published: 2019-12-09
Updated: 2019-12-09
Packaged: 2021-02-26 02:00:12
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 669
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21735673
Author URL: https://archiveofourown.org/users/placeholder000/pseuds/placeholder000
Summary: You want Mutt to pull you apart in ways his brother never wants to.
Relationships: Papyrus (Undertale)/Reader, Papyrus (Undertale)/You, Papyrus/Sans (Undertale), Sans (Undertale)/Reader, Sans (Undertale)/You
Comments: 17
Kudos: 57





	Bittersweet Infidelity

**Author's Note:**

> I had read a post where someone had mentioned something about having a Mutt/Reader where Mutt just loathes the reader. I wrote something like a while ago on it and now I thought of a way to finish it.

“Do you ever think we should just stop doing this?”

The question wants to clear your mouth but you are too busy biting down on your shirt in a futile attempt to keep quiet as the Mutt keeps pounding into you, aggressively taking out his hatred out on your body. 

“You make my lord so weak, with your pathetic softness, this seductive flesh” He pants out, pausing in his assault to grope at you, his rough touch easily bruising you. You should speak up, tell him that this can’t go on, Sans deserves better than the both of you, but you don’t. You take his harsh touches, his harsh thrusting because you feel like you deserve it. He grinds his thumb against your clit painfully but it’s the pain you yearn for. A few loveless strokes you cum around his cock. He pauses and almost looks like he’s going to stop, but he just adjusts his arms above you.

“Pathetic” he mutters and continues to use you. 

You deserve this, this loveless fucking, after all, you lust for him, how low can you be? In a loving tender relationship with his older brother but all you want is for Papyrus to fuck your brains out. Sans treats you like a doll, something that could be easily broken when all you want to be is broken. It made for a frustrating relationship. No matter how much you asked Sans to degrade you, to be rougher as you “made love” the best you got from him was a light smack on the ass as he took you from behind. 

You almost cried in relief when his brother shoved you against a wall the first moment you were alone for more than 5 minutes. He growled out a warning to you, that nothing could come between them, especially a pathetic human like yourself. That you were just an infatuation Sans had for now and soon it would just be him and Sans like it always was and always would be. 

He had smelled your arousal and that sealed your fate, instead of being disgusted with you he had given you a smirk and ripped your pants off. He had fucked you against the wall that day, just purging his loathing of you deep inside and you relished the burn of the wall scraping your back, cumming harder than you ever had with Sans.

After that day a pattern emerged, Papyrus would seethe quietly for a few weeks until he came to a breaking point and would corner you when Sans left for work and fuck your brains out.

If Sans noticed the bruises or the smell of his brother on you he never said anything about it. Instead, he would treat you to the aftercare Papyrus never would. Sans would clean you, bundle you up and you would both watch movies in his bed on a laptop. 

A grunt breaks you from your memories as Papyrus cums inside you. He thrusts one more time his bones rattling with his release. He sighs and without a word pulls out and leaves, pulling up his pants as he walks towards the door.

You stay on the bed, not wanting to move. Trying not to cry as crushing guilt overwhelms you.

Papyrus looks at you spread out on the bed, his cum leaking out of you. He looks like he wants to say something, his eyes almost going soft before he leers at you.

“clean yourself up pet, and change the damn sheets.” He turns back to the door, opens it, but before he can leave you finally get the words out.

“Do you ever think we should just stop doing this?”

He pauses halfway through the doorway.

"are you going to ever admit that you don't love him?"

You're silent, and your silence damns you. 

He chuckles without humor "that's what I thought". He leaves, not even closing the door. 

You wrap yourself up with the blanket on the bed and begin to cry.


End file.
